What’s Vulnerable › Vulnerabilities

CVE-2026-78209: exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-24 · updated 2026-10-14
• Weakness: CWE-1236

Description

exceljs through 4.4.0 fails to neutralize leading equals, plus, minus, or at signs in cell values written to CSV output. Attackers who can influence exported cell values can inject formulas that execute when the CSV file is opened in a spreadsheet application, potentially exfiltrating data or performing other malicious actions.

Affected products

• exceljs: through 4.4.0

References

• https://github.com/exceljs/exceljs
• https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182
• https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw
• https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values

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